Apparatus and method for cleaning abrasively treated plastic webs



Feb. 2, 1960 Filed Dec. 8,

2 Sheets-Sheet 1 P. H. PELLEY APPARATUS AND METHOD Po LEANING ABRAsIvELYTREATED PLA C wEBs 1955 s? :i M aldllfl Q a @I l I TS* l ,Ig

INVENTOR.

PERRY H. PEL/.EY

Attorney Feb. 2, 1960 P. H. PELLEY 2,923,109

APPARATUS AND METHOD FOR CLEANING ABRAsIvELY TREATED PLASTIC WEBS FiledDec. 8, 1955 2 Sheets-Sheet 2 INVENTOR.

PERRY h'. PELLEY Jell@ Affarney United States Patent O APPARATUS ANDMETHOD FOR CLEANING ABRASIVELY TREATED PLASTHC WEBS Perry H. Pelley,Wichita, Kans., assignor to Tru-Scale, Inc., Wichita, Kans., acorporation of Kansas Application December 8, 1955, Serial No. 551,887

' s claims. (c1. s1-2sz) This invention relates to an apparatus andmethod for cleaning abrasively-treated plastic webs and moreparticularly for removing residual abrasive granules from the surfacesof a continuous web of organic synthetic resinous material which hasbeen treated by hurling abrasive granules against one surface thereofwith abrasive throwing wheels.

When continuous plastic webs are abrasively treated by means ofcentrifugal abrasive throwing wheels in the manner described inco-pending applications Serial No. 551,885, filed December 8, 1955 andSerial No. 551,886, filed December 8, 1955 a certain residue of abrasivegranules remains adherent to the treated surface thereof and also to theuntreated surface thereof and it is neces.- sary to provide means forremoving such granules in order to provide a finished web which willmeet the requirements of industry with respect to appearance andadherence. Dust created by the abrasive treating action also remainsadherent to the web and must be removed. A large portion of the abrasivegranules and a certain portion of the dust is removed by conventionalmechanical means such as by jets of air directed against one or bothsurfaces of the web and may be removed by such conventional means aspassing the dry webs against rotating brushes. However, these methodsare ineffective to remove a certain residual portion of abrasivegranules and dust which are suicient to cause the web to be rejected forindustrial applications unless the surfaces be further treated orcleaned to remove such material.

It is conventional to further treat a continuous web of metal which hasbeen abrasively treated by passing it through acid pickling baths,through aqueous baths containing detergents and by like methods in orderto accomplish such further cleaning. In the instant case suchconventional cleaning methods are inadequate with respect to webs havingorganic synthetic resinous surfaces for reasons which are not altogetherunderstood but which appear to arise from the factl that a certainelectrical attraction exists between such dirt and a web which comprisesorganic synthetic resin. It is therefore an object of this invention toprovide an apparatus and method for cleaning a continuous web comprisingorganic synthetic resinous material which has been treated bycentrifugally throwing abrasive granules against one or both of thesurfaces thereof.

Further objects will become apparent from the drawings and the followingdetailed description in which it is my intention to illustrate theapplicability of the invention without thereby restricting its scope toless than that of all those equivalents which will be apparent to oneskilled in the art.

In the drawings like reference numerals refer to like parts and:

Figure 1 is a partially cutaway schematic perspective view of apparatusfor abrasively treating a surface of a continuous web and apparatus forcleaning residual dirt from the web in accordance with the invention;

ice

Figure 2 is a partially cut-away schematic perspective view of anotherembodiment of apparatus for removin dirt from an abrasively treated web;

Figure 3 is an enlarged, partially cut-away, schematic perspective viewof reciprocating brushes which may form a part of the apparatus ofFigure 2;

Figure 4 is a cross-sectional view of a brush which may be used in theapparatus of Figures 2 and 3;

i Figure 5 is a partially cut-away perspective'view of anotherembodiment of apparatus for cleaning residual dirt from anabrasively-treated web; and

Figure 6 is a partially cross-sectional, partially perspective view ofan air knife such as may be used inthe embodiments of Figures 2 and 5.

Referring now to Figure 1 there is shown a device for abrasivelytreating one surface of a plastic web comprising a housing 5. At one endof housing 5 there is provided storage or feed-roll 3 for web 2 whichmay be as described elsewhere herein. Roll 8 is provided withV drag orbrake means adapted to resist unwinding of theweb therefrom and therebyto provide tension in the web. Illustration of such means, which arewell known in the art, has been omitted for the sake of simplicity.Inoue end of housing 5 there is provided slot 9 through which web 2 mayenter the housing and near slot 9 there is provided direction-changingroll 10 over which the web may pass. At the opposlte end of housing 5there is provided cleaning means indicated generally as 12 for removingresidual abrasive granules from the web and there is provided dryingmeans indicated generally as 79 and also idler roll 14 over which theweb may pass and wind-up roll 16 which may be driven by any suitablemeans, which for the sake of simplicity have not been illustrated.Driving means for roll 16 may suitably comprise an electric motor and avariable speed drive of any one of the types well known in the art.Within housing 5 there may be provided back-up belt 18 which may travelcontinuously in the direction shown over rolls 19 and 20. The lower runmay travel in an arcuately downward curve and may be supported in such acurve by shoe 21 disposed against the inner surface thereof; if desiredthe upper run of belt 18 may be supported by a shoe, such as shoe 22.Near the ends of belt 18 there may be provided idler rolls 24 and 26over which web 2 may be caused to pass and these may be so arranged asto cause the web to be maintained against the lower run of beit 18'byreason of the tension in the web created by the driving or pulling forceof windup roll 16 acting against the resistance of feed roll 8. Withinthe cabinet and below belt 18 are located two throwing wheels 27 and 30.Wheel 30 may be driven by motor 32 through belts 31 or through any othersuitable drive and wheel 27 may be driven similarly by motor 29 throughbelts 28. The throwing wheels may be of any conventional type describedin the art, for example, as described in U.S. Patent 2,170,831. f

ln place or' centrifugal throwing means comprising wheels 2l and 30 forprojecting granules against the web in order to accomplish the abrasivetreating of the surface thereof, there may be used any other suitablemeans for hurling abrasive granules at high velocity against the surfaceof a web (such as, for example, sand blasting or vapor blasting devices)wherein abrasive granules are conveyed from a storage reservoir, thencethrough a conveying tube and thence through a nozzle and against thesurface of a web by means of a current of liquid media passing throughthe reservoir, the tube and the nozzle with the granules. Such liquidmedia may be air or steam or may in some cases be a liquid such as wateror a mixture of water and steam. However, for compelling economic andpracticed reasons centrifugal throwing wheels have been foundpreferable.

Housing 5 may be provided with a grating floor 34 and with a hopperedbottom 36 which may extend downwardly into Ia Vsuitablerpit provided inconcrete Vbase 37. Hoppered ybottom 3 6 may open into the lower end offlight elevator 38 provided with flights 39.

web2 may travel from roll 8 over roll 10 and over l'Oll 24, thencethrough slot 9 and 4against the lower surface of belt 18. It may thenpass through a `slot 11 in wall 40 which may ybe provided to minimizethe distribution Ofrandom granules of abrasive within housing 5. It maythen pass over idler roll 26 and below cleaning nozzle 42 which may blowair against the upper surface to Vremove residual granules of abrasivetherefrom. Itmay then pass through slot l13 in the wall of yhousing 5and thence through cleaning apparatus 12 to wind-up roll 16. Abrasivegranules thrown against the lower surface of web 2 by wheels 27 and 30rebound ,therefrom and may thence strike various portions of theinterior of housing 5 and rebound several more times so that theinterior portion of housing 5 tends to be filled with reboundingabrasive. Therefore a certain amountof abrasive collects on the uppersurface of web 2 and this may be removed for the most part by air blownfrom nozzle 42. However, a certain amount of residual abrasive granulesremains adherent to both surfaces of the web and must be removed bycleaning device 12. Abrasive thrown by Wheels 27 and 30, afterrebounding falls by gravity to the bottom of hopper 36 and thence iscarried upwardly by ights 39 and elevator 38. At the top of elevator 38it is unloaded into a cleaning chamber 48 at the top of hopper 54.

In cleaning chamber 48 large particles of foreign matter, tramp iron andthe like may be removed by conventional screening devices, which, forthe sake of simplicity, have not been shown. Clean abrasive granulesfall into hopper 54 from chamber 48 and may pass downward therefromthrough conventional well-known metering devices and thence throughtubes 56 and 58 into the hubs of wheels 27 and 30.

The air which is introduced into housing 5 by nozzle 42 passes downwardthrough grating floor 34 and upward through elevator 38 and thenceoutward through duct 60 into cyclone separator 62. Dust-laden airpassing outward from the top of cyclone separator 62 through duct 68 maybe introduced into device 70 which may remove residual light-weight dustfrom the air by causing it to pass through suitable fabric lter clothsand the air thus cleaned may be drawn outward from device 70 by blower66. The draft within housing 5 and elevator 38 is provided by thecombined actions of blower 43 introducing air at nozzle 42 and blowerV66. Relatively heavy dust removed from the kair in cyclone Vseparator62 may pass downward through tube 63 into housing S from whence it maybe recycled. Within cleaning chamber `48 a current of air may be causedto pass through a cascade of abrasive falling therefrom into hopper 54and relatively light weight dust is thus removed from the abrasivegranules and caused to be suspended in the air, which may pass thencethrough duct 69 to device 70.

The cleaning means indicated generally as 12 may suitably comprise twotanks 71 and 72 adapted to contain liquid baths and a plurality of idlerdirection-changing rolls 75vfor leading the web through these tanks insuccession. A greater number of tanks may suitably be used lif desiredbut generally two tanks have been found sufficient. There may becontained in tank 71 an aqueous solution 76 of non-foaming detergent,which also may contain a mild abrasive scouring material as more fullydescribed hereinafter and there may be contained within tank 72 cleanrinse vC'ater 78. Immersed in solution 76 contained in tank 71 there maybe provided two brushes 80 and 82 provided with means for causing themto be reciprocated cross-wise with respect to the direction of advanceof the web and these brushes may, if desired, be provided with back-uprolls 81 and 83 adapted to maintain the web in contact with the bristlesthereof. Also immersed in solution 76 contained in tank 71 there may beprovided rotating brushes 84 and 86 disposed in such manner as tooperate against opposite sides of the web and in conjunction with thesebrushes there may be provided back-up rolls 85 and 87 adapted to holdthe web in contact with the bristles thereof. immersed in the water 73or other rinsing liquid contained in tank 72 there may be'rprovided tworotating brushes 90 and 92 adapted to operate against opposite sides ofthe web. These may be provided with back-up rolls in the manner thatbrushes 84 and 86 are so provided but back-up rolls are not necessaryAfor the proper functioning of the brushes and may be omitted, as shown,if desired. lt is essential to the proper functioning of the device thatthe brushes be operated against the surfaces of the web while both weband brushes are immersed in a liquid such as water, with respect towhich the web is chemically inert.

The mode of operation will be apparent from the previous description ofthedevice. A continuous web is abrasively treated in the device byinstalling in suitable holding means a roll 8 of web material and thenthreading the web through the machine in the manner indicated. By thendriving wind-up roll 16, by means not shown, to cause it to rotate inthe direction indicated bythe arrow, the web is pulled through themachine and maintained in close contact with the lower run of belt 18.As the centrifugal throwing wheels are rotated, abrasive enters the hubsof these wheels and is centrifugally thrown upward against theunder-surface of the web by the vanes or blades in the wheels. Residualgranules on the surface of the web are removed by cleaning device 12 andthe web is dried by drier 79 and then wound on roll 16.

Referring now to Figure 2 there is shown another embodiment of apparatusfor satisfactorily cleaning the surfaces of a web which have beenabrasively treated by hurling abrasive granules thereagainst withcentrifugal throwing means or other devices as previously described. Aweb 2 may pass in the direction shown by the arrows from anabrasive-treating device indicated generally as 4 through tanks 101 and102, thence through drying means indicated generally as 79 and thence towind-up roll 16. Idler rolls may be so located as to cause web 2,threaded thereover in the manner shown, to pass respectively throughsolution 106 contained in tank 101 and then through solution 108contained in tank 102. As shown in Figures 2, 3, and 4, there may beprovided in each of tanks 101 and 102, below the surface of liquids 106and 108 contained therein, brushes 109. In each tank one brush mayoperate against one side of the web and the other brush against theother side of the web. Brushes 109 are desirably reciprocated crosswsewith respect to the direction of advance of the web and this may beaccomplished, as shown in Figure 3 by providing tanks 101 and 102 withsupporting plates 132 and with supports 111 and 112 extendingrespectively therefrom and provided at the extremities thereof withhingepins 115 and 116 adapted to serve as fulcrums for levers 117 and118. The upper ends of levers 117 and 118 may be connected throughconnecting rods 119 and 120 to cranks 121 and 122 carried on theopposite ends of shaft 123, which may be driven by motor 125 throughbelt 126 operating on pulley 127 also carried by said shaft 123.

. By this mechanism the rotary motion of motor 125 is converted intooscillatory motion shafts of levers 117 and 118. Main brush supportingrods 130 which may be square or rectangular extend through similarlyshaped holes 131 in supporting plates 132 contained within tanks 101and'102 and may thereby prevent the brushes from rotating while atthesame time allowing them to be recprocated. The ends of the upper andlower bars 130 in tank 102 are respectively connected by links 137 and138 to lever 118 above and below pin 116. The oscillatory motion oflevers 117 and 118 is thus translated by links 135 to 138 intoreciprocating motion of bars 130.l Bars 130 may have attached theretoback plates 140. On each side of bar 130 there may be provided two rows141 of bristles attached to back plate 140 by means of channels 142having wedging members 143 located between the webs thereof in suchmanner as to. provide twobristle-retaining grooves within each ofmembers 142. Other suitable means for retaining rows of bristlesattached to a relatively rigid backing member are well known in the artand any one of such methods or devices which provides adequate retentionfor the bristles may suitably be used for the device of the invention.

As-the web passes upward out of liquid 108 contained in tank 102 it maypass between air knives 150 and 151. Each of air knives 150 and 151 maybe constructed as shown in Figure 6, or in any other suitable manneradapted to provide a slot comparable to slot 153 which may be lpreciseand uniform in its width and to provide a flow of air therethrough whichhas a negligible differential in velocity between anytwo points alongthe length of the slot. As shown, an air knife may suitably be made byattaching to three stringers 154 back plates 155 and front plates 156which may be provided with precisely machined sharp edges 157 and 158which may be spaced apart at some predetermined distance such as .020inches to provide a slot of precise width such as slot 153. Air may beintroduced into the device through a tube such as tube 159.

The web may then pass through a drier such as 79' or 79. Each of driers79 and 79 comprises a plurality of rods 73 on each side of the web whichwhen electrically heated are adapted to emit heating radiation of highiutensity. Reflector plates 74 and 77 respectively may be provided tocause such radiation, which would otherwise be lost, to be reflectedagainst the web. The particular means of heating the web in order tocause it to be dried is not essential to the invention and othersuitable means such as hot air ovens, drying tunnels and the like maysuitably be utilized.

From drying means 79 the web may pass over a slat expander roll 160 anda pair of idler rolls 161 and 162 adapted to maintain the webin Contactwith major portion of the surface of roll 160. Roll 160 may be a slatexpanding idler roll as shown or any other roll adapted to causewrinkles to be removed from a thin web. The mode or functioning of slatexpander rolls is well known in the art and need not be here furtherdescribed except to state that roll 160 presents to the web an outersurface consisting of the outer surfaces of a plurality of slats in twosets. One set consists of slats extending parallel to the axis of theroll from about the center of lthe roll to one end thereof and the otherset consists of slats extending similarly from about the center to theother end thereof; each slat in one set corresponds to a slat in theother Slat and mechanical means, such as ca m means, are provided tocause each of the two slats in such a pair to simultaneously traverselongitudinally, that is parallel to the axis of the roll, so that as theroll rotates a greater or lesser distance is provided between the endsof each of the members of a pair. As each pair cornes in contact with -aweb, this distance is at a minimum and the distance is graduallyincreased until at the time the web leaves the roll the distance is at amaximum, each slat sliding frictionally over the surface of the web insuch manner as to cause it to be smoothed in a manner similar to thatwhich may be accomplished by two persons standing on opposite sides ofthe web and pulling outwardly on the edge ad- A brushes.

jacent each. Since the nature and mode of operation of expander rollssuch as roll is not essential to the invention, such rolls will not bedescribed or illustrated in further detail.

Referring now to Figure 5 there is shown another ernbodiment of theinvention wherein web 2 is caused to pass successively through solutions206 and 208 contained in tanks 201 and 202, passing in the directionshown by the arrows, over idler rolls 205. Disposed below the surface ofliquids 206 and 208 are a plurality of powered rotating brushes 209located in such manner as to cause each of the surfaces of the web to bebrushed in each of the tanks below the surface of the liquid containedtherein. Power may be provided for the brushes by any suitable means,such as an electric motor 220 driving through belt 221 which may engagepulleys (not shown) attached to the roll. After passing through liquids206 and 208 and being brushed beneath the surfaces thereof, the webpasses upward between air knives and thence through dryer 279 whichmay-comprise an oven 271 provided with gas burners 272 adapted to heatthe air therein. The web may then pass over smoothing roll 160 and idlerrolls 161 and 162 to wind up roll 16.

In operation a web is passed through a rst tank containing a washingsolution wherein both surfaces of the web are brushed below the surfaceof the solution. The web may then be passed if desired through one ormore additional washing solutions and if desired brushed on either oneor both surfaces while immersed in such solutions but generally it hasbeen found suicient to pass the web through only one washing solution.After being washed the web may be passed through one or more tankscontaining a rinsing liquid; for purposes of the invention, clear waterhas generally been found suitable as a rinsing liquid. It is preferredto brush both surfaces of the web while the web is immersed in therinsing liquid. If desired, each surface of the web may be brushed belowthe surface of the liquid by more than one brush in each of the washingtanks and in each lof the rinsing tanks. lt has generally been foundsuitable for the purposes of the invention to brush each surface of theweb once while the web is immersed in one washing solution and in onerinsing solution. A minimum of tanks and a minimum of brushes is ofcourse preferred for reasons of economy but it is not intended that theillustration of only one tank for washing the web and only one tank forrinsing the web in each of the embodiments of the invention be taken aslimiting or preferred for reasons other than economy nor is it to beunderstood that the number of brushes shown precludes the use of manymore It is essential to the invention that each surface of the web bebrushed below the surface of at least one washing solution. Backup rollsfor the brushes may be used if desired, but are not necessary. A largeportion of the water which clings to the web as the web leaves the rinsetank may be removed by means of air knives. In place of a pair of airknives as shown in Figures 2 and 5, a single air knife may be utilizedto remove rinsing liquid from one side of the web, and if desired abackup roll may be provided opposite such a single air knife in order tomaintain the spacing of the surface of the web with respect thereto. l

The invention has been found particularly suitable for cleaning webscomprising polyester synthetic resins, both linear thermoplasticsynthetic resins such as polyethylene terephthalate sold commercially asMylar by du Pont de Nemours and thermosetting polyester synthetic resinswhich are almost invariably reinforced with such materials as wovencotton fabric, wovenglass fabric, unwoven fibrous glass reinforcing mator paper. Such polyester resins comprise the product of copolymerizing amonomer having a single terminal ethylenic group such as styrene withthe product obtained by reacting a multihydroxy alcohol with anethylenic alpha-beta-dicarboxylic acid such as maleic, fumaric,itaconic, adipic acid -or the like. Suitable as dihydroxy alcohols areethylene glycol, diethylene glycol, -triethylene glycol and propyleneglycol. In place of styrene there may be used any one of a large numberof unsaturates well -known in the art such as vinyl acetate, dia'llyl-phosphenate, diallyl phthalate and the like. Other organic `syntheticresinous materials of which the invention is particularly suitableinclude thermosetting melamine formaldehyde resins, thermosetting ureaformaldehyde resins, thermosetting phenol formaldehyde resins, andgenerally thermosetting polymers of compounds containing active amine orphenol groups with formaldehyde or formaldehyde-generating compoundssuch as hexamethylene tetramine. Thermoplastic resinous webs -may alsobe treated according to the invention although modification of theprocess may be necessary for this purpose and the results obtained aregenerally not equally desirable. Such vresins may include polymethylmethacrylate, polyvinyl acetate, polyvinyl chlorideacetate, -polyvinylchloride, polyvinylidene chloride, cellulose acetate, cellulose acetatebutyrate, etc.

-It is essential vthat there be contained in the washing liquid both adetergent which maybe dissolved in Water to provide an aqueous washingsolution and a material believed-to function as a mild abrasive whichcan best be described as suspended therein. Asa detergent thereis-preferred an :alkyl-phenyl ether of polyethylene glycol soldcommercially as NP-27 by the Carbide & Carbon Chemical Corporation; achemically similar alkyl phenyl ether of polyethylene glycol sold underthe designation NP-l4 by the same company is almost equally good.Mixtures of these two'materials, aswell as mixtures of ei ther or bothof these with other detergents, are also suitable and there may also beused an alkyl phenyl ether of polyethylene glycol sold commercially -asTriton X-lOO by Rohm and Haas or the compound Kelite sold by the KeliteChemical Company. Denatured ethyl alcohol has been found particularlyeffective as a detergent 'when added in sufficient amount to provide a50% solution of denatured ethyl alcohol in water. Although the use of anon-foaming detergent is not necessarily essential for accomplishingwashing action, it is made almost imparative `by reason of the extremekturbulence which is created by the brushes which would Vcause anexcess. of foam and suds to be generated if any other type were used.

It has been particularly surprisingly found that a most satisfactoryadditive to the washing bath consists of a quantity,.preferably.relatively large, of ,dust of a type it is desired to remove in .thevwashing operation. As has been previously described, such dust isremoved in device 70 from the air which traverses the interior ofhousing 5 and elevator ,38. Dust .removed by the fabric filter clothswithindeviee 7,0 `may be added to the detergent solution contained inthe Wash-,bath in an amount as greatas-one pound of dust per gallon ofsolution to provide superior washing action. It is believed this dustfunctions as `a mild scouring powder or abrasive but its action may beelectrical in nature. Other albrasive agents may also be suitable.

The `air knives are particularly effective in removing not only waterwhich clings to the web, but in removing dirt which remains suspended insuch rinse water which clings to the web and which in the absence of theair knives is redeposited upon the web when the water evaporates. Y

Itis preferable to maintain the water in the rinse bath as c lean aspossible and this may be accomplished by directing a constant stream offresh water thereinto and providing an overow means of any conventionaltype. Y

It may thus be seen that the invention is broad in scope andis not to belimited excepting by the claims.

Having thus disclosed by invention, I claim:

1. The method of providing a continuous web com# prising organicsynthetic resinous material Awith a clean matte surface which comprisesthe steps of continuously advancing such a web, continuously abrasivelytreating a surface of said web to provide said surface with a mattefinish having particles of abrasive and particles of abraded webmaterial thereon, then advancing said web into an aqueous washing bath,adding particles abraded from such a web to said bath to provide a mildscouring abrasive therein, mechanically brushing said surface of saidweb while immersed in said bath to remove said particles of abrasive andsaid particles of abraded web material from said treated surface andthen rinsing and drying the web.

2. The method of providing a continuous web comprising organic syntheticresinous material with a clean matte surface which comprises the stepsof continuously advancing such a web, continuously abrasively treating asurface of said web to provide said surface with a matte finish havingparticles of abrasive and particles of abraded web material thereon,then removing at least some of said particles of abrasive and abradedweb material and separating thus removed particles of abrasive from thusremoved particles of web material, then advancing said web havingremaining particles of abrasive and remaining particles of abraded webmaterial on said surface into an aqueous washing bath, adding suchparticles of abraded web material abraded and removed from such a web tosaid bath to provide a mild scouring abrasive therein, mechanicallybrushing said surface of said web while immersed in said bath to removesaid remaining particles of abrasive and said remaining particles ofabraded web material from said treated surface and then rinsing anddrying the web.

3. The method of providing a continuous web comprising organic syntheticresinous material with a clean matte surface which comprises the stepsof continuously advancing such a web, continuously abrasively treating asurface of said web to provide said surface with a matte finish havingparticles of abrasive and particles of abraded web material thereon,then removing at least some of said particles of abrasive and abradedweb material and separating thus removed particles of abrasive from thusremoved particles of web material, then advancing said web havingremaining particles of abrasive and remaining particles of abraded webmaterial on said surface into an aqueous washing bath, adding saidremoved particles of abraded web material abraded from said web to saidbath to provide a mild scouring abrasive therein, mechanically brushingsaid surface of said web while immersed in said bath to remove saidremaining particles of abrasive and said remaining particles of abradedweb material from said treated surface and then rinsing and drying theweb.

4. The method of removing particles of abrasive and particles of webmaterial from a surface of a continuous web comprising organic syntheticresinous material which has been abraded with said abrasive to producesaid particles of web material, which comprises the steps of providingan aqueous Washing bath, adding some of such particles of web materialabraded from such a web to said bath to provide a mild scouringVabrasive therein, continuously advancing said web into said bath andmechanically brushing said surface of -said web while immersed in saidbath and then rinsing and drying the web.

5. The method of removing particles of abrasive and particles of webmaterial from a surface of a continuous web comprising organic syntheticresinous material which has been abraded with said abrasive to producesaid particles of web material, which comprises the steps of providingan aqueous washing bath, adding some of said particles of web materialabraded from said web to said bath to provide a mild scouring abrasivetherein, continuously advancing said web into said bath and mechanicallybrushing said surface of said web while the web.

References Cited in the .le f this patent UNITED STATES PATENTS DeMoosApr.'5, 1927 Ellis May 8, 1928 OBrien July 24, 1928 Hands June 23, 1931Wynd Oct. 17, 1933 Wean May 31, 1938 Minch ---2., Oct. 4, 1938 -LesavoyAug. 31, 1948 Wallace ...g Dec. 16, 1952 Vander Wal 1.--- Ian. 13, 1953Grillette et al. July 13, 1954 Castagnoli Mar. 13, 1956 Prince May 15,1956 Curtin Dec. 24, 1957 FOREIGN PATENTS Franse Mar. 29, 1927

